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            <div class="post-toc animated"><ol class="nav"><li class="nav-item nav-level-1"><a class="nav-link" href="#%E4%B8%80%E3%80%81%E6%A0%B8%E5%BF%83%E6%95%B0%E6%8D%AE%E7%BB%93%E6%9E%84"><span class="nav-text">一、核心数据结构</span></a><ol class="nav-child"><li class="nav-item nav-level-2"><a class="nav-link" href="#1-%E5%85%B3%E9%94%AE%E6%95%B0%E6%8D%AE%E7%BB%93%E6%9E%84"><span class="nav-text">1. 关键数据结构</span></a><ol class="nav-child"><li class="nav-item nav-level-3"><a class="nav-link" href="#1-1-configfs-attribute"><span class="nav-text">1.1 configfs_attribute</span></a></li><li class="nav-item nav-level-3"><a class="nav-link" href="#1-2-config-item"><span class="nav-text">1.2 config_item</span></a></li><li class="nav-item nav-level-3"><a class="nav-link" href="#1-3-config-group"><span class="nav-text">1.3 config_group</span></a></li><li class="nav-item nav-level-3"><a class="nav-link" href="#1-4-configfs-subsystem"><span class="nav-text">1.4 configfs_subsystem</span></a></li><li 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<details class="folding-tag" blue><summary> 点击查看使用工具及版本 </summary>
              <div class='content'>
              <table>    <tr>        <td align="center" rowspan="5">PC端开发环境</td>        <td align="center" width=150px>Windows</td>        <td align="left">Windows11</td>    </tr>    <tr>        <td align="center">Ubuntu</td>        <td align="left">Ubuntu20.04.2的64位版本</td>      </tr>    <tr>        <td align="center">VMware® Workstation 17 Pro</td>        <td align="left">17.6.0 build-24238078</td>      </tr>    <tr>        <td align="center">终端软件</td>        <td align="left">MobaXterm(Professional Edition v23.0 Build 5042 (license))</td>    </tr>    <tr>        <td align="center">Win32DiskImager</td>        <td align="left">Win32DiskImager v1.0</td>      </tr>    <tr>        <td align="center" rowspan="3">Linux开发板环境</td>        <td align="center">Linux开发板</td>        <td align="left">正点原子 i.MX6ULL Linux 阿尔法开发板</td>      </tr>    <tr>        <td align="center">uboot</td>        <td align="left">NXP官方提供的uboot，使用的uboot版本为U-Boot 2019.04</td>      </tr>    <tr>        <td align="center">linux内核</td>        <td align="left">linux-4.19.71(NXP官方提供)</td>      </tr></table>
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<details class="folding-tag" blue><summary> 点击查看本文参考资料 </summary>
              <div class='content'>
              <table>    <tr>        <td align="center">分类</td>        <td align="center">网址</td>        <td align="center">说明</td>    </tr>    <tr>        <td align="center" rowspan="5">官方网站</td>        <td align="left"><a href="https://www.arm.com/" target="_blank">https://www.arm.com/</a></td>        <td align="left">ARM官方网站，在这里我们可以找到Cotex-Mx以及ARMVx的一些文档</td>    </tr>    <tr>        <td align="left"><a href="https://www.nxp.com.cn/" target="_blank">https://www.nxp.com.cn/ </a></td>        <td align="left">NXP官方网站</td>    </tr>    <tr>        <td align="left"><a href="https://www.nxpic.org.cn/" target="_blank">https://www.nxpic.org.cn/</a></td><td align="left">NXP 官方社区</td>    </tr>    <tr>        <td align="left"><a href="https://u-boot.readthedocs.io/en/latest/" target="_blank">https://u-boot.readthedocs.io/en/latest/</a></td><td align="left">u-boot官网</td>    </tr>    <tr>        <td align="left"><a href="https://www.kernel.org/" target="_blank">https://www.kernel.org/</a></td><td align="left">linux内核官网</td>    </tr></table>
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<details class="folding-tag" blue><summary> 点击查看相关文件下载 </summary>
              <div class='content'>
              <table>    <tr>        <td align="center">分类</td>        <td align="center">网址</td>        <td align="center">说明</td>    </tr>    <tr>        <td align="center" rowspan="3">NXP</td>        <td align="left"><a href="https://github.com/nxp-imx" target="_blank">https://github.com/nxp-imx</a></td>        <td align="left">NXP imx开发资源GitHub组织，里边会有u-boot和linux内核的仓库</td>    </tr>    <tr>        <td align="left"><a href="https://github.com/nxp-imx/linux-imx/releases/tag/v4.19.71" target="_blank">nxp-imx/linux-imx/releases/tag/v4.19.71</a></td>        <td align="left">NXP linux内核仓库tags中的v4.19.71</td>    </tr>    <tr>        <td align="left"><a href="https://github.com/nxp-imx/uboot-imx/releases/tag/rel_imx_4.19.35_1.1.0" target="_blank">nxp-imx/uboot-imx/releases/tag/rel_imx_4.19.35_1.1.0</a></td>        <td align="left">NXP u-boot仓库tags中的rel_imx_4.19.35_1.1.0</td>    </tr>    <tr>        <td align="center" rowspan="2">I.MX6ULL</td>        <td align="left"><a href="https://www.nxp.com.cn/docs/en/data-sheet/IMX6ULLIEC.pdf" target="_blank">i.MX 6ULL Applications Processors for Industrial Products</a></td>        <td align="left">I.MX6ULL 芯片手册（datasheet，可以在线查看）</td>    </tr>    <tr>        <td align="left"><a href="https://www.nxp.com.cn/webapp/Download?colCode=IMX6ULLRM&lang_cd=zh" target="_blank">i.MX 6ULL Applications ProcessorReference Manual</a></td>        <td align="left">I.MX6ULL 参考手册（下载后才能查看，需要登录NXP官网）</td>    </tr>    <tr>        <td align="center" rowspan="3">Source Code</td>        <td align="left"><a href="https://elixir.bootlin.com/linux/latest/source" target="_blank">https://elixir.bootlin.com/linux/latest/source</a></td>        <td align="left">linux kernel源码</td>    </tr>    <tr>        <td align="left"><a href="https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/?h=v4.19.71&id=e7d2672c66e4d3675570369bf20856296da312c4" target="_blank">kernel/git/stable/linux.git - Linux kernel stable tree</a></td>        <td align="left">linux kernel源码(官网,tag 4.19.71)</td>    </tr>    <tr>        <td align="left"><a href="https://elixir.bootlin.com/u-boot/latest/source" target="_blank">https://elixir.bootlin.com/u-boot/latest/source</a></td>        <td align="left">uboot源码</td>    </tr></table>
              </div>
            </details>

<p>这一部分是学习如何创建内核对象， 然后生成对应的文件和目录。  </p>
<h1 id="一、核心数据结构"><a href="#一、核心数据结构" class="headerlink" title="一、核心数据结构"></a><font size=3>一、核心数据结构</font></h1><h2 id="1-关键数据结构"><a href="#1-关键数据结构" class="headerlink" title="1. 关键数据结构"></a><font size=3>1. 关键数据结构</font></h2><p>站在用户的角度来说，一个文件系统里面有目录、文件两种对象。在configfs的内核实现中，对应4个概念。</p>
<h3 id="1-1-configfs-attribute"><a href="#1-1-configfs-attribute" class="headerlink" title="1.1 configfs_attribute"></a><font size=3>1.1 <a target="_blank" rel="noopener" href="https://elixir.bootlin.com/linux/v4.19.17/source/include/linux/configfs.h#L131">configfs_attribute</a></font></h3><p>这里其实还有个<a target="_blank" rel="noopener" href="https://elixir.bootlin.com/linux/v4.19.17/source/include/linux/configfs.h#L167">configfs_bin_attribute</a>，他们两个都是对应文件。</p>
<ul>
<li><a target="_blank" rel="noopener" href="https://elixir.bootlin.com/linux/v4.19.17/source/include/linux/configfs.h#L131">configfs_attribute</a>：对应的文件里含有的是可视化的字符串信息</li>
</ul>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br></pre></td><td class="code"><pre><span class="line"><span class="class"><span class="keyword">struct</span> <span class="title">configfs_attribute</span> &#123;</span></span><br><span class="line">	<span class="type">const</span> <span class="type">char</span>		*ca_name;</span><br><span class="line">	<span class="class"><span class="keyword">struct</span> <span class="title">module</span> 		*<span class="title">ca_owner</span>;</span></span><br><span class="line">	<span class="type">umode_t</span>			ca_mode;</span><br><span class="line">	<span class="type">ssize_t</span> (*show)(<span class="keyword">struct</span> config_item *, <span class="type">char</span> *);</span><br><span class="line">	<span class="type">ssize_t</span> (*store)(<span class="keyword">struct</span> config_item *, <span class="type">const</span> <span class="type">char</span> *, <span class="type">size_t</span>);</span><br><span class="line">&#125;;</span><br></pre></td></tr></table></figure>

<ul>
<li><a target="_blank" rel="noopener" href="https://elixir.bootlin.com/linux/v4.19.17/source/include/linux/configfs.h#L167">configfs_bin_attribute</a>：对应的文件里含有的是二进制信息</li>
</ul>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br></pre></td><td class="code"><pre><span class="line"><span class="class"><span class="keyword">struct</span> <span class="title">configfs_bin_attribute</span> &#123;</span></span><br><span class="line">	<span class="class"><span class="keyword">struct</span> <span class="title">configfs_attribute</span> <span class="title">cb_attr</span>;</span>	<span class="comment">/* std. attribute */</span></span><br><span class="line">	<span class="type">void</span> *cb_private;			<span class="comment">/* for user       */</span></span><br><span class="line">	<span class="type">size_t</span> cb_max_size;			<span class="comment">/* max core size  */</span></span><br><span class="line">	<span class="type">ssize_t</span> (*read)(<span class="keyword">struct</span> config_item *, <span class="type">void</span> *, <span class="type">size_t</span>);</span><br><span class="line">	<span class="type">ssize_t</span> (*write)(<span class="keyword">struct</span> config_item *, <span class="type">const</span> <span class="type">void</span> *, <span class="type">size_t</span>);</span><br><span class="line">&#125;;</span><br></pre></td></tr></table></figure>

<p>（1）读写文件时，会导致上述结构体里的show&#x2F;store或者read&#x2F;write函数被调用</p>
<p>（2）文件是位于某个目录的: config_item</p>
<h3 id="1-2-config-item"><a href="#1-2-config-item" class="headerlink" title="1.2 config_item"></a><font size=3>1.2 <a target="_blank" rel="noopener" href="https://elixir.bootlin.com/linux/v4.19.17/source/include/linux/configfs.h#L54">config_item</a></font></h3><figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br></pre></td><td class="code"><pre><span class="line"><span class="class"><span class="keyword">struct</span> <span class="title">config_item</span> &#123;</span></span><br><span class="line">	<span class="type">char</span>			*ci_name;</span><br><span class="line">	<span class="type">char</span>			ci_namebuf[CONFIGFS_ITEM_NAME_LEN];</span><br><span class="line">	<span class="class"><span class="keyword">struct</span> <span class="title">kref</span>		<span class="title">ci_kref</span>;</span></span><br><span class="line">	<span class="class"><span class="keyword">struct</span> <span class="title">list_head</span>	<span class="title">ci_entry</span>;</span></span><br><span class="line">	<span class="class"><span class="keyword">struct</span> <span class="title">config_item</span>	*<span class="title">ci_parent</span>;</span></span><br><span class="line">	<span class="class"><span class="keyword">struct</span> <span class="title">config_group</span>	*<span class="title">ci_group</span>;</span></span><br><span class="line">	<span class="type">const</span> <span class="class"><span class="keyword">struct</span> <span class="title">config_item_type</span>	*<span class="title">ci_type</span>;</span></span><br><span class="line">	<span class="class"><span class="keyword">struct</span> <span class="title">dentry</span>		*<span class="title">ci_dentry</span>;</span></span><br><span class="line">&#125;;</span><br><span class="line"></span><br></pre></td></tr></table></figure>

<p>这是 ConfigFS 中最基本的数据结构， 用于表示一个配置项。 每个配置项都是一个内核对象， 可以是设备、 驱动程序、 子系统等。 config_item 结构包含了配置项的类型、名称、 属性、 状态等信息， 以及指向父配置项和子配置项的指针。</p>
<blockquote>
<p>Tips：configfs中的每个对象都是config_item，后面的config_group、subsystem本质上都属于特殊的config_item </p>
</blockquote>
<ul>
<li><a target="_blank" rel="noopener" href="https://elixir.bootlin.com/linux/v4.19.17/source/include/linux/configfs.h#L93">config_group</a>、<a target="_blank" rel="noopener" href="https://elixir.bootlin.com/linux/v4.19.17/source/include/linux/configfs.h#L240">configfs_subsystem</a>，<a target="_blank" rel="noopener" href="https://elixir.bootlin.com/linux/v4.19.17/source/include/linux/configfs.h#L54">config_item</a>都对应一个目录</li>
<li>跟<a target="_blank" rel="noopener" href="https://elixir.bootlin.com/linux/v4.19.17/source/include/linux/configfs.h#L93">config_group</a>、<a target="_blank" rel="noopener" href="https://elixir.bootlin.com/linux/v4.19.17/source/include/linux/configfs.h#L240">configfs_subsystem</a>对比时， <a target="_blank" rel="noopener" href="https://elixir.bootlin.com/linux/v4.19.17/source/include/linux/configfs.h#L54">config_item</a>这个<strong>目录下不再有目录</strong></li>
<li>在  <a target="_blank" rel="noopener" href="https://elixir.bootlin.com/linux/v4.19.17/source/include/linux/configfs.h#L54">config_item</a> 目录下有属性文件，还可以创建链接文件</li>
<li>链接文件的操作结构体是：<a target="_blank" rel="noopener" href="https://elixir.bootlin.com/linux/v4.19.17/source/include/linux/configfs.h#L81">config_item_type</a>里的 <a target="_blank" rel="noopener" href="https://elixir.bootlin.com/linux/v4.19.17/source/include/linux/configfs.h#L226">configs_item_operations</a></li>
</ul>
<img data-src="https://fanhua-picture.oss-cn-hangzhou.aliyuncs.com/01%E5%B5%8C%E5%85%A5%E5%BC%8F%E5%BC%80%E5%8F%91/02IMX6ULL%E5%B9%B3%E5%8F%B0/LV06-%E9%A9%B1%E5%8A%A8%E5%BC%80%E5%8F%91/LV06-12-ConfigFS-02-%E6%95%B0%E6%8D%AE%E7%BB%93%E6%9E%84%E4%B8%8E%E5%BA%94%E7%94%A8/img/116_config_item.png" alt="image-20230328101747270"  />

<h3 id="1-3-config-group"><a href="#1-3-config-group" class="headerlink" title="1.3 config_group"></a><font size=3>1.3 <a target="_blank" rel="noopener" href="https://elixir.bootlin.com/linux/v4.19.17/source/include/linux/configfs.h#L93">config_group</a></font></h3><p><a target="_blank" rel="noopener" href="https://elixir.bootlin.com/linux/v4.19.17/source/include/linux/configfs.h#L93">config_group</a> 是一种特殊类型的配置项， 表示一个配置项组，对应一个目录。 它可以包含一组相关的配置项， 形成一个层次结构。<a target="_blank" rel="noopener" href="https://elixir.bootlin.com/linux/v4.19.17/source/include/linux/configfs.h#L93">config_group</a> 结构包含了父配置项的指针， 以及指向子配置项的链表。</p>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br></pre></td><td class="code"><pre><span class="line"><span class="class"><span class="keyword">struct</span> <span class="title">config_group</span> &#123;</span></span><br><span class="line">	<span class="class"><span class="keyword">struct</span> <span class="title">config_item</span>		<span class="title">cg_item</span>;</span></span><br><span class="line">	<span class="class"><span class="keyword">struct</span> <span class="title">list_head</span>		<span class="title">cg_children</span>;</span></span><br><span class="line">	<span class="class"><span class="keyword">struct</span> <span class="title">configfs_subsystem</span> 	*<span class="title">cg_subsys</span>;</span></span><br><span class="line">	<span class="class"><span class="keyword">struct</span> <span class="title">list_head</span>		<span class="title">default_groups</span>;</span></span><br><span class="line">	<span class="class"><span class="keyword">struct</span> <span class="title">list_head</span>		<span class="title">group_entry</span>;</span></span><br><span class="line">&#125;;</span><br></pre></td></tr></table></figure>

<ul>
<li>普通的<a target="_blank" rel="noopener" href="https://elixir.bootlin.com/linux/v4.19.17/source/include/linux/configfs.h#L54">config_item</a> ：下面不再有子目录。</li>
<li><a target="_blank" rel="noopener" href="https://elixir.bootlin.com/linux/v4.19.17/source/include/linux/configfs.h#L93">config_group</a>：下面还可以创建<a target="_blank" rel="noopener" href="https://elixir.bootlin.com/linux/v4.19.17/source/include/linux/configfs.h#L54">config_item</a>或者<a target="_blank" rel="noopener" href="https://elixir.bootlin.com/linux/v4.19.17/source/include/linux/configfs.h#L93">config_group</a>，即：下面可以再创建子目录。</li>
<li>在当前目录下操作子目录时，对应的操作结构体是：<a target="_blank" rel="noopener" href="https://elixir.bootlin.com/linux/v4.19.17/source/include/linux/configfs.h#L81">config_item_type</a>里的 <a target="_blank" rel="noopener" href="https://elixir.bootlin.com/linux/v4.19.17/source/include/linux/configfs.h#L232">configs_group_operations</a><img data-src="https://fanhua-picture.oss-cn-hangzhou.aliyuncs.com/01%E5%B5%8C%E5%85%A5%E5%BC%8F%E5%BC%80%E5%8F%91/02IMX6ULL%E5%B9%B3%E5%8F%B0/LV06-%E9%A9%B1%E5%8A%A8%E5%BC%80%E5%8F%91/LV06-12-ConfigFS-02-%E6%95%B0%E6%8D%AE%E7%BB%93%E6%9E%84%E4%B8%8E%E5%BA%94%E7%94%A8/img/117_config_group.png" alt="image-20230328103059600"  /></li>
</ul>
<h3 id="1-4-configfs-subsystem"><a href="#1-4-configfs-subsystem" class="headerlink" title="1.4 configfs_subsystem"></a><font size=3>1.4 <a target="_blank" rel="noopener" href="https://elixir.bootlin.com/linux/v4.19.17/source/include/linux/configfs.h#L240">configfs_subsystem</a></font></h3><p><a target="_blank" rel="noopener" href="https://elixir.bootlin.com/linux/v4.19.17/source/include/linux/configfs.h#L240">configfs_subsystem</a> 是configfs文件系中的最顶层的数据结构， 用于表示整个 ConfigFS 子系统。 它包含了根配置项组的指针， 以及 ConfigFS 的其他属性和状态信息。</p>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br></pre></td><td class="code"><pre><span class="line"><span class="class"><span class="keyword">struct</span> <span class="title">configfs_subsystem</span> &#123;</span></span><br><span class="line">	<span class="class"><span class="keyword">struct</span> <span class="title">config_group</span>	<span class="title">su_group</span>;</span></span><br><span class="line">	<span class="class"><span class="keyword">struct</span> <span class="title">mutex</span>		<span class="title">su_mutex</span>;</span></span><br><span class="line">&#125;;</span><br></pre></td></tr></table></figure>

<ul>
<li><p>比如：<code>/sys/kernel/config/usb_gadget</code>、<code>/sys/kernel/config/iio</code></p>
</li>
<li><p>在<code>drivers/usb/gadget/configfs.c</code>中调用<code>configfs_register_subsystem(&amp;gadget_subsys)</code>就会创建subsystem，它对应configfs文件系统中的顶层目录<code>usb_gadget</code></p>
</li>
<li><p>subsystem也属于<a target="_blank" rel="noopener" href="https://elixir.bootlin.com/linux/v4.19.17/source/include/linux/configfs.h#L93">config_group</a>。</p>
</li>
</ul>
<img data-src="https://fanhua-picture.oss-cn-hangzhou.aliyuncs.com/01%E5%B5%8C%E5%85%A5%E5%BC%8F%E5%BC%80%E5%8F%91/02IMX6ULL%E5%B9%B3%E5%8F%B0/LV06-%E9%A9%B1%E5%8A%A8%E5%BC%80%E5%8F%91/LV06-12-ConfigFS-02-%E6%95%B0%E6%8D%AE%E7%BB%93%E6%9E%84%E4%B8%8E%E5%BA%94%E7%94%A8/img/118_subsystem.png" alt="image-20230328103329215"  />

<h3 id="1-5-总结"><a href="#1-5-总结" class="headerlink" title="1.5 总结"></a><font size=3>1.5 总结</font></h3><p>这些数据结构之间的关系可以形成一个树形结构， 其中 configfs_subsystem 是根节点， config_group 表示配置项组， config_item 表示单个配置项。 子配置项通过链表连接在一起， 形成父子关系。   </p>
<img data-src="https://fanhua-picture.oss-cn-hangzhou.aliyuncs.com/01%E5%B5%8C%E5%85%A5%E5%BC%8F%E5%BC%80%E5%8F%91/02IMX6ULL%E5%B9%B3%E5%8F%B0/LV06-%E9%A9%B1%E5%8A%A8%E5%BC%80%E5%8F%91/LV06-12-ConfigFS-02-%E6%95%B0%E6%8D%AE%E7%BB%93%E6%9E%84%E4%B8%8E%E5%BA%94%E7%94%A8/img/image-20250307100009404.png" alt="image-20250307100009404"  />

<h2 id="2-子系统、-容器和-config-item"><a href="#2-子系统、-容器和-config-item" class="headerlink" title="2. 子系统、 容器和 config_item "></a><font size=3>2. 子系统、 容器和 <a target="_blank" rel="noopener" href="https://elixir.bootlin.com/linux/v4.19.17/source/include/linux/configfs.h#L54">config_item</a> </font></h2><p>接下来以设备树插件的驱动为例来详细了解一下这三个概念。</p>
<h3 id="2-1-dtbocfg-root-subsys"><a href="#2-1-dtbocfg-root-subsys" class="headerlink" title="2.1 dtbocfg_root_subsys"></a><font size=3>2.1 dtbocfg_root_subsys</font></h3><figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br></pre></td><td class="code"><pre><span class="line"><span class="type">static</span> <span class="class"><span class="keyword">struct</span> <span class="title">configfs_subsystem</span> <span class="title">dtbocfg_root_subsys</span> =</span> &#123;</span><br><span class="line">    .su_group = &#123;</span><br><span class="line">        .cg_item = &#123;</span><br><span class="line">            .ci_namebuf = <span class="string">&quot;device-tree&quot;</span>,</span><br><span class="line">            .ci_type    = &amp;dtbocfg_root_type,</span><br><span class="line">        &#125;,</span><br><span class="line">    &#125;,</span><br><span class="line">  .su_mutex = __MUTEX_INITIALIZER(dtbocfg_root_subsys.su_mutex),</span><br><span class="line">&#125;;</span><br><span class="line"></span><br></pre></td></tr></table></figure>

<p>这段代码定义了一个名为 dtbocfg_root_subsys 的 <a target="_blank" rel="noopener" href="https://elixir.bootlin.com/linux/v4.19.17/source/include/linux/configfs.h#L240">configfs_subsystem</a> 结构体实例， 表示ConfigFS 中的一个子系统。  </p>
<ul>
<li><a target="_blank" rel="noopener" href="https://elixir.bootlin.com/linux/v4.19.17/source/include/linux/configfs.h#L241">dtbocfg_root_subsys.su_group</a> 是一个 <a target="_blank" rel="noopener" href="https://elixir.bootlin.com/linux/v4.19.17/source/include/linux/configfs.h#L93">config_group</a> 结构体， 它表示子系统的根配置项组。 在这里， 该结构体的 <a target="_blank" rel="noopener" href="https://elixir.bootlin.com/linux/v4.19.17/source/include/linux/configfs.h#L94">.cg_item</a> 字段表示根配置项组的基本配置项。</li>
</ul>
<p>.ci_namebuf &#x3D; “device-tree”： 配置项的名称设置为”device-tree”， 表示该配置项的名称为”device-tree”。</p>
<p>.ci_type &#x3D; &amp;dtbocfg_root_type： 配置项的类型设置为 dtbocfg_root_type， 这是一个自定义的配置项类型。</p>
<ul>
<li>.su_mutex 字段是一个互斥锁， 用于保护子系统的操作。 在这里， 使用了__MUTEX_INITIALIZER 宏来初始化互斥锁。</li>
</ul>
<p>通过这段代码， 创建了一个名为”device-tree”的子系统， 它的根配置项组为空。 可以在该子系统下添加更多的配置项和配置项组， 用于动态配置和管理设备树相关的内核对象。 Linux系统下创建了 device-tree 这个子系统,如下图 :</p>
<p><img data-src="https://fanhua-picture.oss-cn-hangzhou.aliyuncs.com/01%E5%B5%8C%E5%85%A5%E5%BC%8F%E5%BC%80%E5%8F%91/02IMX6ULL%E5%B9%B3%E5%8F%B0/LV06-%E9%A9%B1%E5%8A%A8%E5%BC%80%E5%8F%91/LV06-12-ConfigFS-02-%E6%95%B0%E6%8D%AE%E7%BB%93%E6%9E%84%E4%B8%8E%E5%BA%94%E7%94%A8/img/image-20250307141505657.png" alt="image-20250307141505657"></p>
<h3 id="2-2-注册配置项组"><a href="#2-2-注册配置项组" class="headerlink" title="2.2 注册配置项组  "></a><font size=3>2.2 注册配置项组  </font></h3><p>接下来继续分析设备树插件驱动代码中注册配置项组的部分 ：</p>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br></pre></td><td class="code"><pre><span class="line"><span class="type">static</span> <span class="type">int</span> __init <span class="title function_">dtbocfg_module_init</span><span class="params">(<span class="type">void</span>)</span></span><br><span class="line">&#123;</span><br><span class="line">    <span class="type">int</span> retval = <span class="number">0</span>;</span><br><span class="line"></span><br><span class="line">    pr_info(DRIVER_NAME <span class="string">&quot;: &quot;</span> DRIVER_VERSION <span class="string">&quot;\n&quot;</span>);</span><br><span class="line"></span><br><span class="line">    config_group_init(&amp;dtbocfg_root_subsys.su_group);</span><br><span class="line">    config_group_init_type_name(&amp;dtbocfg_overlay_group, <span class="string">&quot;overlays&quot;</span>, &amp;dtbocfg_overlays_type);</span><br><span class="line"></span><br><span class="line">    retval = configfs_register_subsystem(&amp;dtbocfg_root_subsys);</span><br><span class="line">    <span class="keyword">if</span> (retval != <span class="number">0</span>) &#123;</span><br><span class="line">        pr_err( <span class="string">&quot;%s: couldn&#x27;t register subsys\n&quot;</span>, __func__);</span><br><span class="line">        <span class="keyword">goto</span> register_subsystem_failed;</span><br><span class="line">    &#125;</span><br><span class="line"></span><br><span class="line">    retval = configfs_register_group(&amp;dtbocfg_root_subsys.su_group, &amp;dtbocfg_overlay_group);</span><br><span class="line">    <span class="keyword">if</span> (retval != <span class="number">0</span>) &#123;</span><br><span class="line">        pr_err( <span class="string">&quot;%s: couldn&#x27;t register group\n&quot;</span>, __func__);</span><br><span class="line">        <span class="keyword">goto</span> register_group_failed;</span><br><span class="line">    &#125;</span><br><span class="line"></span><br><span class="line">    pr_info(DRIVER_NAME <span class="string">&quot;: OK\n&quot;</span>);</span><br><span class="line">    <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line"></span><br><span class="line">  register_group_failed:</span><br><span class="line">    configfs_unregister_subsystem(&amp;dtbocfg_root_subsys);</span><br><span class="line">  register_subsystem_failed:</span><br><span class="line">    <span class="keyword">return</span> retval;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>

<p>这段代码是一个初始化函数 dtbocfg_module_init()， 用于初始化和注册 ConfigFS 子系统和配置项组。</p>
<ul>
<li><p>第 7 行：通过 <a target="_blank" rel="noopener" href="https://elixir.bootlin.com/linux/v4.19.17/source/fs/configfs/item.c#L169">config_group_init()</a>函数初始化了 <a target="_blank" rel="noopener" href="https://elixir.bootlin.com/linux/v4.19.17/source/include/linux/configfs.h#L241">dtbocfg_root_subsys.su_group</a>， 即子系统的根配置项组。   </p>
</li>
<li><p>第 8 行：使用 <a target="_blank" rel="noopener" href="https://elixir.bootlin.com/linux/v4.19.17/source/fs/configfs/item.c#L108">config_group_init_type_name()</a>函数初始化了dtbocfg_overlay_group， 表示名为”overlays”的配置项组， 并指定了配置项组的类型为dtbocfg_overlays_type， 这是一个自定义的配置项类型。   </p>
</li>
<li><p>第 10 行：调用 <a target="_blank" rel="noopener" href="https://elixir.bootlin.com/linux/v4.19.17/source/fs/configfs/dir.c#L1854">configfs_register_subsystem()</a>函数注册了 dtbocfg_root_subsys 子系统。 如果注册失败， 将打印错误信息， 并跳转到register_subsystem_failed 标签处进行错误处理。   </p>
</li>
<li><p>第 16 行：调用 <a target="_blank" rel="noopener" href="https://elixir.bootlin.com/linux/v4.19.17/source/fs/configfs/dir.c#L1733">configfs_register_group()</a>函数注册了 dtbocfg_overlay_group 配置项组， 并将其添加到 dtbocfg_root_subsys.su_group 下。 如果注册失败， 同样会打印错误信息， 并跳转到 register_group_failed 标签处进行错误处理。   </p>
</li>
<li><p>第 22 - 23 行：如果所有的注册过程都成功， 将打印”OK”消息， 并返回 0， 表示初始化成功。</p>
</li>
</ul>
<p>如果在注册配置项组失败时， 会先调用 <a target="_blank" rel="noopener" href="https://elixir.bootlin.com/linux/v4.19.17/source/fs/configfs/dir.c#L1902">configfs_unregister_subsystem()</a> 函数注销之前注册的子系统， 然后返回注册失败的错误码 retval。这段代码的作用是初始化和注册一个名为”device-tree”的 ConfigFS 子系统， 并在其下创建一个名为”overlays”的配置项组。 Linux 系统下， 在 device-tree 子系统下创建了 overlays 容器，如下图 ：</p>
<p><img data-src="https://fanhua-picture.oss-cn-hangzhou.aliyuncs.com/01%E5%B5%8C%E5%85%A5%E5%BC%8F%E5%BC%80%E5%8F%91/02IMX6ULL%E5%B9%B3%E5%8F%B0/LV06-%E9%A9%B1%E5%8A%A8%E5%BC%80%E5%8F%91/LV06-12-ConfigFS-02-%E6%95%B0%E6%8D%AE%E7%BB%93%E6%9E%84%E4%B8%8E%E5%BA%94%E7%94%A8/img/image-20250307142437264.png" alt="image-20250307142437264"></p>
<h2 id="3-属性和方法"><a href="#3-属性和方法" class="headerlink" title="3. 属性和方法  "></a><font size=3>3. 属性和方法  </font></h2><p>我们要在容器下放目录或属性文件， 所以我们看一下 <a target="_blank" rel="noopener" href="https://elixir.bootlin.com/linux/v4.19.17/source/include/linux/configfs.h#L54">config_item</a>结构体 ：</p>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br></pre></td><td class="code"><pre><span class="line"><span class="class"><span class="keyword">struct</span> <span class="title">config_item</span> &#123;</span></span><br><span class="line">	<span class="type">char</span>			*ci_name;</span><br><span class="line">	<span class="type">char</span>			ci_namebuf[CONFIGFS_ITEM_NAME_LEN]; <span class="comment">// 目录的名字</span></span><br><span class="line">	<span class="class"><span class="keyword">struct</span> <span class="title">kref</span>		<span class="title">ci_kref</span>;</span></span><br><span class="line">	<span class="class"><span class="keyword">struct</span> <span class="title">list_head</span>	<span class="title">ci_entry</span>;</span></span><br><span class="line">	<span class="class"><span class="keyword">struct</span> <span class="title">config_item</span>	*<span class="title">ci_parent</span>;</span></span><br><span class="line">	<span class="class"><span class="keyword">struct</span> <span class="title">config_group</span>	*<span class="title">ci_group</span>;</span></span><br><span class="line">	<span class="type">const</span> <span class="class"><span class="keyword">struct</span> <span class="title">config_item_type</span>	*<span class="title">ci_type</span>;</span> <span class="comment">// 目录下属性文件和属性操作</span></span><br><span class="line">	<span class="class"><span class="keyword">struct</span> <span class="title">dentry</span>		*<span class="title">ci_dentry</span>;</span></span><br><span class="line">&#125;;</span><br><span class="line"></span><br></pre></td></tr></table></figure>

<p><a target="_blank" rel="noopener" href="https://elixir.bootlin.com/linux/v4.19.17/source/include/linux/configfs.h#L54">config_item</a> 结构体中包含了 <a target="_blank" rel="noopener" href="https://elixir.bootlin.com/linux/v4.19.17/source/include/linux/configfs.h#L81">config_item_type</a> 结构体， <a target="_blank" rel="noopener" href="https://elixir.bootlin.com/linux/v4.19.17/source/include/linux/configfs.h#L81">config_item_type</a> 结构体如下所示:</p>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br></pre></td><td class="code"><pre><span class="line"><span class="class"><span class="keyword">struct</span> <span class="title">config_item_type</span> &#123;</span></span><br><span class="line">	<span class="class"><span class="keyword">struct</span> <span class="title">module</span>				*<span class="title">ct_owner</span>;</span></span><br><span class="line">	<span class="class"><span class="keyword">struct</span> <span class="title">configfs_item_operations</span>		*<span class="title">ct_item_ops</span>;</span>  <span class="comment">// item（目录） 的操作方法</span></span><br><span class="line">	<span class="class"><span class="keyword">struct</span> <span class="title">configfs_group_operations</span>	*<span class="title">ct_group_ops</span>;</span> <span class="comment">// group（容器） 的操作方法</span></span><br><span class="line">	<span class="class"><span class="keyword">struct</span> <span class="title">configfs_attribute</span>		**<span class="title">ct_attrs</span>;</span>        <span class="comment">// 属性文件的操作方法</span></span><br><span class="line">	<span class="class"><span class="keyword">struct</span> <span class="title">configfs_bin_attribute</span>		**<span class="title">ct_bin_attrs</span>;</span><span class="comment">// bin 属性文件的操作方法</span></span><br><span class="line">&#125;;</span><br></pre></td></tr></table></figure>

<ul>
<li><a target="_blank" rel="noopener" href="https://elixir.bootlin.com/linux/v4.19.17/source/include/linux/configfs.h#L81">config_item_type</a> 结构体中包含了 <a target="_blank" rel="noopener" href="https://elixir.bootlin.com/linux/v4.19.17/source/include/linux/configfs.h#L226">struct configfs_item_operations</a> 结构体:</li>
</ul>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br></pre></td><td class="code"><pre><span class="line"><span class="class"><span class="keyword">struct</span> <span class="title">configfs_item_operations</span> &#123;</span></span><br><span class="line">    <span class="comment">// 删除 item 方法， 在 group 下面使用 rmdir 命令会调用这个方法</span></span><br><span class="line">	<span class="type">void</span> (*release)(<span class="keyword">struct</span> config_item *);</span><br><span class="line">	<span class="type">int</span> (*allow_link)(<span class="keyword">struct</span> config_item *src, <span class="keyword">struct</span> config_item *target);</span><br><span class="line">	<span class="type">void</span> (*drop_link)(<span class="keyword">struct</span> config_item *src, <span class="keyword">struct</span> config_item *target);</span><br><span class="line">&#125;;</span><br></pre></td></tr></table></figure>

<ul>
<li><a target="_blank" rel="noopener" href="https://elixir.bootlin.com/linux/v4.19.17/source/include/linux/configfs.h#L81">config_item_type</a> 结构体中包含了 <a target="_blank" rel="noopener" href="https://elixir.bootlin.com/linux/v4.19.17/source/include/linux/configfs.h#L232">struct configfs_group_operations</a> 结构体：</li>
</ul>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br></pre></td><td class="code"><pre><span class="line"><span class="class"><span class="keyword">struct</span> <span class="title">configfs_group_operations</span> &#123;</span></span><br><span class="line">    <span class="comment">//创建 item 的方法， 在 group 下面使用 mkdir 命令会调用这个方法</span></span><br><span class="line">	<span class="class"><span class="keyword">struct</span> <span class="title">config_item</span> *(*<span class="title">make_item</span>)(<span class="keyword">struct</span> <span class="title">config_group</span> *<span class="title">group</span>, <span class="title">const</span> <span class="title">char</span> *<span class="title">name</span>);</span></span><br><span class="line">    <span class="comment">//创建 group 的方法</span></span><br><span class="line">	<span class="class"><span class="keyword">struct</span> <span class="title">config_group</span> *(*<span class="title">make_group</span>)(<span class="keyword">struct</span> <span class="title">config_group</span> *<span class="title">group</span>, <span class="title">const</span> <span class="title">char</span> *<span class="title">name</span>);</span></span><br><span class="line">	<span class="type">int</span> (*commit_item)(<span class="keyword">struct</span> config_item *item);</span><br><span class="line">	<span class="type">void</span> (*disconnect_notify)(<span class="keyword">struct</span> config_group *group, <span class="keyword">struct</span> config_item *item);</span><br><span class="line">	<span class="type">void</span> (*drop_item)(<span class="keyword">struct</span> config_group *group, <span class="keyword">struct</span> config_item *item);</span><br><span class="line">&#125;;</span><br></pre></td></tr></table></figure>

<ul>
<li><a target="_blank" rel="noopener" href="https://elixir.bootlin.com/linux/v4.19.17/source/include/linux/configfs.h#L81">config_item_type</a>  结构体中包含了 <a target="_blank" rel="noopener" href="https://elixir.bootlin.com/linux/v4.19.17/source/include/linux/configfs.h#L131">struct configfs_attribute</a>结构体：</li>
</ul>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br></pre></td><td class="code"><pre><span class="line"><span class="class"><span class="keyword">struct</span> <span class="title">configfs_attribute</span> &#123;</span></span><br><span class="line">	<span class="type">const</span> <span class="type">char</span>		*ca_name; <span class="comment">// 属性文件的名字</span></span><br><span class="line">	<span class="class"><span class="keyword">struct</span> <span class="title">module</span> 	*<span class="title">ca_owner</span>;</span><span class="comment">// 属性文件文件的所属模块</span></span><br><span class="line">	<span class="type">umode_t</span>			ca_mode;  <span class="comment">// 属性文件访问权限</span></span><br><span class="line">    </span><br><span class="line">    <span class="comment">// 读写方法的函数指针， 具体功能需要自行实现。</span></span><br><span class="line">	<span class="type">ssize_t</span> (*show)(<span class="keyword">struct</span> config_item *, <span class="type">char</span> *);</span><br><span class="line">	<span class="type">ssize_t</span> (*store)(<span class="keyword">struct</span> config_item *, <span class="type">const</span> <span class="type">char</span> *, <span class="type">size_t</span>);</span><br><span class="line">&#125;;</span><br></pre></td></tr></table></figure>

<h2 id="4-总结"><a href="#4-总结" class="headerlink" title="4. 总结"></a><font size=3>4. 总结</font></h2><ul>
<li><a target="_blank" rel="noopener" href="https://elixir.bootlin.com/linux/v4.19.17/source/include/linux/configfs.h#L240">configfs_subsystem</a></li>
</ul>
<img data-src="https://fanhua-picture.oss-cn-hangzhou.aliyuncs.com/01%E5%B5%8C%E5%85%A5%E5%BC%8F%E5%BC%80%E5%8F%91/02IMX6ULL%E5%B9%B3%E5%8F%B0/LV06-%E9%A9%B1%E5%8A%A8%E5%BC%80%E5%8F%91/LV06-12-ConfigFS-02-%E6%95%B0%E6%8D%AE%E7%BB%93%E6%9E%84%E4%B8%8E%E5%BA%94%E7%94%A8/img/image-20250313090707277.png" alt="image-20250313090707277"  />

<ul>
<li><a target="_blank" rel="noopener" href="https://elixir.bootlin.com/linux/v4.19.17/source/include/linux/configfs.h#L93">config_group</a></li>
</ul>
<img data-src="https://fanhua-picture.oss-cn-hangzhou.aliyuncs.com/01%E5%B5%8C%E5%85%A5%E5%BC%8F%E5%BC%80%E5%8F%91/02IMX6ULL%E5%B9%B3%E5%8F%B0/LV06-%E9%A9%B1%E5%8A%A8%E5%BC%80%E5%8F%91/LV06-12-ConfigFS-02-%E6%95%B0%E6%8D%AE%E7%BB%93%E6%9E%84%E4%B8%8E%E5%BA%94%E7%94%A8/img/image-20250313090813358.png" alt="image-20250313090813358"  />

<ul>
<li><a target="_blank" rel="noopener" href="https://elixir.bootlin.com/linux/v4.19.17/source/include/linux/configfs.h#L54">config_item</a></li>
</ul>
<img data-src="https://fanhua-picture.oss-cn-hangzhou.aliyuncs.com/01%E5%B5%8C%E5%85%A5%E5%BC%8F%E5%BC%80%E5%8F%91/02IMX6ULL%E5%B9%B3%E5%8F%B0/LV06-%E9%A9%B1%E5%8A%A8%E5%BC%80%E5%8F%91/LV06-12-ConfigFS-02-%E6%95%B0%E6%8D%AE%E7%BB%93%E6%9E%84%E4%B8%8E%E5%BA%94%E7%94%A8/img/image-20250313090903830.png" alt="image-20250313090903830"  />

<ul>
<li>attribute</li>
</ul>
<img data-src="https://fanhua-picture.oss-cn-hangzhou.aliyuncs.com/01%E5%B5%8C%E5%85%A5%E5%BC%8F%E5%BC%80%E5%8F%91/02IMX6ULL%E5%B9%B3%E5%8F%B0/LV06-%E9%A9%B1%E5%8A%A8%E5%BC%80%E5%8F%91/LV06-12-ConfigFS-02-%E6%95%B0%E6%8D%AE%E7%BB%93%E6%9E%84%E4%B8%8E%E5%BA%94%E7%94%A8/img/image-20250313091102610.png" alt="image-20250313091102610"  />

<p>当我们使用<code>mkdir dtbo_demo</code>这个命令创建dtbo_demo这个item的时候，就会调用<a target="_blank" rel="noopener" href="https://elixir.bootlin.com/linux/v4.19.17/source/include/linux/configfs.h#L232">configfs_group_operations</a> .<a target="_blank" rel="noopener" href="https://elixir.bootlin.com/linux/v4.19.17/source/include/linux/configfs.h#L233">make_item</a>方法</p>
<h1 id="二、注册configfs子系统"><a href="#二、注册configfs子系统" class="headerlink" title="二、注册configfs子系统"></a><font size=3>二、注册configfs子系统</font></h1><h2 id="1-demo源码"><a href="#1-demo源码" class="headerlink" title="1. demo源码"></a><font size=3>1. demo源码</font></h2><p>demo源码可以看这里：<a target="_blank" rel="noopener" href="https://gitee.com/sumumm/imx6ull-driver-demo/tree/master/12_configfs_demo/01_configfs_subsystem">12_configfs_demo&#x2F;01_configfs_subsystem · 苏木&#x2F;imx6ull-driver-demo - 码云 - 开源中国</a></p>
<h2 id="2-开发板测试"><a href="#2-开发板测试" class="headerlink" title="2. 开发板测试"></a><font size=3>2. 开发板测试</font></h2><ul>
<li>（1）挂载configfs文件系统</li>
</ul>
<figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">mount -t configfs none /sys/kernel/config</span><br></pre></td></tr></table></figure>

<ul>
<li>（2）加载驱动</li>
</ul>
<figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">insmod sdriver_demo.ko</span><br></pre></td></tr></table></figure>

<img data-src="https://fanhua-picture.oss-cn-hangzhou.aliyuncs.com/01%E5%B5%8C%E5%85%A5%E5%BC%8F%E5%BC%80%E5%8F%91/02IMX6ULL%E5%B9%B3%E5%8F%B0/LV06-%E9%A9%B1%E5%8A%A8%E5%BC%80%E5%8F%91/LV06-12-ConfigFS-02-%E6%95%B0%E6%8D%AE%E7%BB%93%E6%9E%84%E4%B8%8E%E5%BA%94%E7%94%A8/img/image-20250313092623759.png" alt="image-20250313092623759"  />

<ul>
<li>（3）查看注册的子系统</li>
</ul>
<figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">ls /sys/kernel/config/</span><br></pre></td></tr></table></figure>

<img data-src="https://fanhua-picture.oss-cn-hangzhou.aliyuncs.com/01%E5%B5%8C%E5%85%A5%E5%BC%8F%E5%BC%80%E5%8F%91/02IMX6ULL%E5%B9%B3%E5%8F%B0/LV06-%E9%A9%B1%E5%8A%A8%E5%BC%80%E5%8F%91/LV06-12-ConfigFS-02-%E6%95%B0%E6%8D%AE%E7%BB%93%E6%9E%84%E4%B8%8E%E5%BA%94%E7%94%A8/img/image-20250313092724621.png" alt="image-20250313092724621"  />

<ul>
<li>（4）卸载驱动</li>
</ul>
<figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br></pre></td><td class="code"><pre><span class="line">rmmod sdriver_demo.ko</span><br><span class="line">ls /sys/kernel/config/</span><br></pre></td></tr></table></figure>

<img data-src="https://fanhua-picture.oss-cn-hangzhou.aliyuncs.com/01%E5%B5%8C%E5%85%A5%E5%BC%8F%E5%BC%80%E5%8F%91/02IMX6ULL%E5%B9%B3%E5%8F%B0/LV06-%E9%A9%B1%E5%8A%A8%E5%BC%80%E5%8F%91/LV06-12-ConfigFS-02-%E6%95%B0%E6%8D%AE%E7%BB%93%E6%9E%84%E4%B8%8E%E5%BA%94%E7%94%A8/img/image-20250313092830742.png" alt="image-20250313092830742"  />

<h1 id="三、注册group容器"><a href="#三、注册group容器" class="headerlink" title="三、注册group容器"></a><font size=3>三、注册group容器</font></h1><h2 id="1-demo源码-1"><a href="#1-demo源码-1" class="headerlink" title="1. demo源码"></a><font size=3>1. demo源码</font></h2><p>源码可以看这里：<a target="_blank" rel="noopener" href="https://gitee.com/sumumm/imx6ull-driver-demo/tree/master/12_configfs_demo/02_configfs_group">12_configfs_demo&#x2F;02_configfs_group · 苏木&#x2F;imx6ull-driver-demo - 码云 - 开源中国</a></p>
<h2 id="2-开发板测试-1"><a href="#2-开发板测试-1" class="headerlink" title="2. 开发板测试"></a><font size=3>2. 开发板测试</font></h2><ul>
<li>（1）挂载configfs文件系统</li>
</ul>
<figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">mount -t configfs none /sys/kernel/config</span><br></pre></td></tr></table></figure>

<ul>
<li>（2）测试效果</li>
</ul>
<figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br></pre></td><td class="code"><pre><span class="line">insmod sdriver_demo.ko</span><br><span class="line"></span><br><span class="line">ls /sys/kernel/config/</span><br><span class="line">ls /sys/kernel/config/sconfigfs/</span><br><span class="line">ls /sys/kernel/config/sconfigfs/sgroup/</span><br><span class="line"></span><br><span class="line">rmmod sdriver_demo.ko</span><br><span class="line">ls /sys/kernel/config/</span><br></pre></td></tr></table></figure>

<img data-src="https://fanhua-picture.oss-cn-hangzhou.aliyuncs.com/01%E5%B5%8C%E5%85%A5%E5%BC%8F%E5%BC%80%E5%8F%91/02IMX6ULL%E5%B9%B3%E5%8F%B0/LV06-%E9%A9%B1%E5%8A%A8%E5%BC%80%E5%8F%91/LV06-12-ConfigFS-02-%E6%95%B0%E6%8D%AE%E7%BB%93%E6%9E%84%E4%B8%8E%E5%BA%94%E7%94%A8/img/image-20250313094035087.png" alt="image-20250313094035087"  />

<p>我们进入注册生成的 sconfigfs 子系统， 可以看到注册生成的 sgroup 容器。  </p>
<h1 id="四、用户空间创建-item"><a href="#四、用户空间创建-item" class="headerlink" title="四、用户空间创建 item  "></a><font size=3>四、用户空间创建 item  </font></h1><h2 id="1-demo实例"><a href="#1-demo实例" class="headerlink" title="1. demo实例"></a><font size=3>1. demo实例</font></h2><h3 id="1-1-demo源码"><a href="#1-1-demo源码" class="headerlink" title="1.1 demo源码"></a><font size=3>1.1 demo源码</font></h3><p>源码可以看这里：<a target="_blank" rel="noopener" href="https://gitee.com/sumumm/imx6ull-driver-demo/tree/master/12_configfs_demo/03_configfs_item">12_configfs_demo&#x2F;03_configfs_item · 苏木&#x2F;imx6ull-driver-demo - 码云 - 开源中国</a></p>
<h3 id="1-2-开发板测试"><a href="#1-2-开发板测试" class="headerlink" title="1.2 开发板测试"></a><font size=3>1.2 开发板测试</font></h3><ul>
<li>（1）挂载configfs文件系统</li>
</ul>
<figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">mount -t configfs none /sys/kernel/config</span><br></pre></td></tr></table></figure>

<ul>
<li>（2）加载驱动</li>
</ul>
<figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">insmod sdriver_demo.ko</span><br></pre></td></tr></table></figure>

<img data-src="https://fanhua-picture.oss-cn-hangzhou.aliyuncs.com/01%E5%B5%8C%E5%85%A5%E5%BC%8F%E5%BC%80%E5%8F%91/02IMX6ULL%E5%B9%B3%E5%8F%B0/LV06-%E9%A9%B1%E5%8A%A8%E5%BC%80%E5%8F%91/LV06-12-ConfigFS-02-%E6%95%B0%E6%8D%AE%E7%BB%93%E6%9E%84%E4%B8%8E%E5%BA%94%E7%94%A8/img/image-20250313105648767.png" alt="image-20250313105648767"  />

<ul>
<li>（3）创建item</li>
</ul>
<figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br></pre></td><td class="code"><pre><span class="line">cd /sys/kernel/config/sconfigfs/sgroup/</span><br><span class="line">mkdir item_demo</span><br></pre></td></tr></table></figure>

<img data-src="https://fanhua-picture.oss-cn-hangzhou.aliyuncs.com/01%E5%B5%8C%E5%85%A5%E5%BC%8F%E5%BC%80%E5%8F%91/02IMX6ULL%E5%B9%B3%E5%8F%B0/LV06-%E9%A9%B1%E5%8A%A8%E5%BC%80%E5%8F%91/LV06-12-ConfigFS-02-%E6%95%B0%E6%8D%AE%E7%BB%93%E6%9E%84%E4%B8%8E%E5%BA%94%E7%94%A8/img/image-20250313105722490.png" alt="image-20250313105722490"  />

<ul>
<li>（4）删除item</li>
</ul>
<figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br></pre></td><td class="code"><pre><span class="line">cd /sys/kernel/config/sconfigfs/sgroup/</span><br><span class="line">rm -rf item_demo</span><br></pre></td></tr></table></figure>

<img data-src="https://fanhua-picture.oss-cn-hangzhou.aliyuncs.com/01%E5%B5%8C%E5%85%A5%E5%BC%8F%E5%BC%80%E5%8F%91/02IMX6ULL%E5%B9%B3%E5%8F%B0/LV06-%E9%A9%B1%E5%8A%A8%E5%BC%80%E5%8F%91/LV06-12-ConfigFS-02-%E6%95%B0%E6%8D%AE%E7%BB%93%E6%9E%84%E4%B8%8E%E5%BA%94%E7%94%A8/img/image-20250313105818715.png" alt="image-20250313105818715"  />

<ul>
<li>（5）卸载驱动</li>
</ul>
<figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">rmmod sdriver_demo.ko</span><br></pre></td></tr></table></figure>

<h2 id="2-drop-item-和-release"><a href="#2-drop-item-和-release" class="headerlink" title="2. drop_item 和 release   "></a><font size=3>2. drop_item 和 release   </font></h2><p>当我们在命令行使用 rmdir 命令删除 item 时， 会执行<a target="_blank" rel="noopener" href="https://elixir.bootlin.com/linux/v4.19.17/source/include/linux/configfs.h#L226">configfs_item_operations</a>.release 函数，</p>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br></pre></td><td class="code"><pre><span class="line"><span class="class"><span class="keyword">struct</span> <span class="title">configfs_item_operations</span> &#123;</span></span><br><span class="line">	<span class="type">void</span> (*release)(<span class="keyword">struct</span> config_item *);</span><br><span class="line">	<span class="type">int</span> (*allow_link)(<span class="keyword">struct</span> config_item *src, <span class="keyword">struct</span> config_item *target);</span><br><span class="line">	<span class="type">void</span> (*drop_link)(<span class="keyword">struct</span> config_item *src, <span class="keyword">struct</span> config_item *target);</span><br><span class="line">&#125;;</span><br></pre></td></tr></table></figure>

<p>.release 成员字段是在 <a target="_blank" rel="noopener" href="https://elixir.bootlin.com/linux/v4.19.17/source/include/linux/configfs.h#L81">struct config_item_type</a>结构体中成员<a target="_blank" rel="noopener" href="https://elixir.bootlin.com/linux/v4.19.17/source/include/linux/configfs.h#L226">configfs_item_operations</a>里面定义的一个回调函数指针。 它指向一个函数， 当 configfs 中的配置项被释放或删除时， 内核会调用该函数来执行相应的资源释放操作。 它通常用于释放与配置项相关的资源， 比如释放动态分配的内存、 关闭打开的文件描述符等。  </p>
<p>还有一个 drop_item 函数，它是定义在 <a target="_blank" rel="noopener" href="https://elixir.bootlin.com/linux/v4.19.17/source/include/linux/configfs.h#L232">configfs_group_operations</a> 中：</p>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br></pre></td><td class="code"><pre><span class="line"><span class="class"><span class="keyword">struct</span> <span class="title">configfs_group_operations</span> &#123;</span></span><br><span class="line">	<span class="class"><span class="keyword">struct</span> <span class="title">config_item</span> *(*<span class="title">make_item</span>)(<span class="keyword">struct</span> <span class="title">config_group</span> *<span class="title">group</span>, <span class="title">const</span> <span class="title">char</span> *<span class="title">name</span>);</span></span><br><span class="line">	<span class="class"><span class="keyword">struct</span> <span class="title">config_group</span> *(*<span class="title">make_group</span>)(<span class="keyword">struct</span> <span class="title">config_group</span> *<span class="title">group</span>, <span class="title">const</span> <span class="title">char</span> *<span class="title">name</span>);</span></span><br><span class="line">	<span class="type">int</span> (*commit_item)(<span class="keyword">struct</span> config_item *item);</span><br><span class="line">	<span class="type">void</span> (*disconnect_notify)(<span class="keyword">struct</span> config_group *group, <span class="keyword">struct</span> config_item *item);</span><br><span class="line">	<span class="type">void</span> (*drop_item)(<span class="keyword">struct</span> config_group *group, <span class="keyword">struct</span> config_item *item);</span><br><span class="line">&#125;;</span><br></pre></td></tr></table></figure>

<p>drop_item 一个回调函数指针。 它指向一个函数， 当 configfs 中的配置组（group） 被删除时， 内核会调用该函数来处理与配置组相关的操作。 这个函数通常用于清理配置组的状态、 释放相关的资源以及执行其他必要的清理操作。 .drop_item 函数在删除配置组时被调用， 而不是在删除单个配置项时被调用。  </p>
<p>.release 成员字段用于<strong>配置项</strong>的释放操作， 而 .drop_item 成员字段用于<strong>配置组</strong>的删除操作。它们分别在不同的上下文中执行不同的任务， 但都与资源释放和清理有关。  </p>
<h2 id="3-drop-item实例"><a href="#3-drop-item实例" class="headerlink" title="3. drop_item实例"></a><font size=3>3. drop_item实例</font></h2><h3 id="2-1-demo源码"><a href="#2-1-demo源码" class="headerlink" title="2.1 demo源码"></a><font size=3>2.1 demo源码</font></h3><p>源码可以看这里：<a target="_blank" rel="noopener" href="https://gitee.com/sumumm/imx6ull-driver-demo/tree/master/12_configfs_demo/04_drop_and_release">12_configfs_demo&#x2F;04_drop_and_release · 苏木&#x2F;imx6ull-driver-demo - 码云 - 开源中国</a></p>
<h3 id="3-2-开发板测试"><a href="#3-2-开发板测试" class="headerlink" title="3.2 开发板测试"></a><font size=3>3.2 开发板测试</font></h3><ul>
<li>（1）挂载configfs文件系统</li>
</ul>
<figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">mount -t configfs none /sys/kernel/config</span><br></pre></td></tr></table></figure>

<ul>
<li>（2）加载驱动</li>
</ul>
<figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">insmod sdriver_demo.ko</span><br></pre></td></tr></table></figure>

<ul>
<li>（3）创建item</li>
</ul>
<figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br></pre></td><td class="code"><pre><span class="line">cd /sys/kernel/config/sconfigfs/sgroup/</span><br><span class="line">mkdir item_demo</span><br></pre></td></tr></table></figure>

<ul>
<li>（4）删除item</li>
</ul>
<figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br></pre></td><td class="code"><pre><span class="line">cd /sys/kernel/config/sconfigfs/sgroup/</span><br><span class="line">rm -rf item_demo</span><br></pre></td></tr></table></figure>

<img data-src="https://fanhua-picture.oss-cn-hangzhou.aliyuncs.com/01%E5%B5%8C%E5%85%A5%E5%BC%8F%E5%BC%80%E5%8F%91/02IMX6ULL%E5%B9%B3%E5%8F%B0/LV06-%E9%A9%B1%E5%8A%A8%E5%BC%80%E5%8F%91/LV06-12-ConfigFS-02-%E6%95%B0%E6%8D%AE%E7%BB%93%E6%9E%84%E4%B8%8E%E5%BA%94%E7%94%A8/img/image-20250313112643471.png" alt="image-20250313112643471"  />

<p>输入“ rmdir test” 命令删除 item， 执行 rmdir 命令之后， 依次执行了 sdrv_group_delete_item() 函数和sdrv_item_release()函数。</p>
<ul>
<li>（5）卸载驱动</li>
</ul>
<figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">rmmod sdriver_demo.ko</span><br></pre></td></tr></table></figure>

<h1 id="五、注册attribute"><a href="#五、注册attribute" class="headerlink" title="五、注册attribute"></a><font size=3>五、注册attribute</font></h1><h2 id="1-demo源码-2"><a href="#1-demo源码-2" class="headerlink" title="1. demo源码"></a><font size=3>1. demo源码</font></h2><p>源码可以看这里：<a target="_blank" rel="noopener" href="https://gitee.com/sumumm/imx6ull-driver-demo/tree/master/12_configfs_demo/05_attribute">12_configfs_demo&#x2F;05_attribute · 苏木&#x2F;imx6ull-driver-demo - 码云 - 开源中国</a></p>
<h2 id="2-开发板测试-2"><a href="#2-开发板测试-2" class="headerlink" title="2. 开发板测试"></a><font size=3>2. 开发板测试</font></h2><ul>
<li>（1）挂载configfs文件系统</li>
</ul>
<figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">mount -t configfs none /sys/kernel/config</span><br></pre></td></tr></table></figure>

<ul>
<li>（2）加载驱动</li>
</ul>
<figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">insmod sdriver_demo.ko</span><br></pre></td></tr></table></figure>

<ul>
<li>（3）创建item</li>
</ul>
<figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br></pre></td><td class="code"><pre><span class="line">cd /sys/kernel/config/sconfigfs/sgroup/</span><br><span class="line">mkdir item_demo</span><br></pre></td></tr></table></figure>

<img data-src="https://fanhua-picture.oss-cn-hangzhou.aliyuncs.com/01%E5%B5%8C%E5%85%A5%E5%BC%8F%E5%BC%80%E5%8F%91/02IMX6ULL%E5%B9%B3%E5%8F%B0/LV06-%E9%A9%B1%E5%8A%A8%E5%BC%80%E5%8F%91/LV06-12-ConfigFS-02-%E6%95%B0%E6%8D%AE%E7%BB%93%E6%9E%84%E4%B8%8E%E5%BA%94%E7%94%A8/img/image-20250313130003520.png" alt="image-20250313130003520"  />

<ul>
<li>（4）属性操作</li>
</ul>
<figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br></pre></td><td class="code"><pre><span class="line">cd item_demo</span><br><span class="line">cat read</span><br><span class="line">echo 1 &gt; write</span><br></pre></td></tr></table></figure>

<img data-src="https://fanhua-picture.oss-cn-hangzhou.aliyuncs.com/01%E5%B5%8C%E5%85%A5%E5%BC%8F%E5%BC%80%E5%8F%91/02IMX6ULL%E5%B9%B3%E5%8F%B0/LV06-%E9%A9%B1%E5%8A%A8%E5%BC%80%E5%8F%91/LV06-12-ConfigFS-02-%E6%95%B0%E6%8D%AE%E7%BB%93%E6%9E%84%E4%B8%8E%E5%BA%94%E7%94%A8/img/image-20250313130056103.png" alt="image-20250313130056103"  />

<ul>
<li>（5）删除item</li>
</ul>
<figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br></pre></td><td class="code"><pre><span class="line">cd /sys/kernel/config/sconfigfs/sgroup/</span><br><span class="line">rmdir item_demo</span><br><span class="line"><span class="meta prompt_"># </span><span class="language-bash">下面这个命令在有属性文件的时候会无权限</span></span><br><span class="line">rm -rf item_demo</span><br></pre></td></tr></table></figure>

<img data-src="https://fanhua-picture.oss-cn-hangzhou.aliyuncs.com/01%E5%B5%8C%E5%85%A5%E5%BC%8F%E5%BC%80%E5%8F%91/02IMX6ULL%E5%B9%B3%E5%8F%B0/LV06-%E9%A9%B1%E5%8A%A8%E5%BC%80%E5%8F%91/LV06-12-ConfigFS-02-%E6%95%B0%E6%8D%AE%E7%BB%93%E6%9E%84%E4%B8%8E%E5%BA%94%E7%94%A8/img/image-20250313130324320.png" alt="image-20250313130324320"  />

<ul>
<li>（5）卸载驱动</li>
</ul>
<figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">rmmod sdriver_demo.ko</span><br></pre></td></tr></table></figure>

<h1 id="六、实现多级目录"><a href="#六、实现多级目录" class="headerlink" title="六、实现多级目录"></a><font size=3>六、实现多级目录</font></h1><p>经过前面的学习， 我们了解到一个配置组也就是（group） 可以包含多个配置项（item）和子配置组。 配置项和配置组都是作为配置组的成员存在的。 配置项和配置组之间通过指针进行关联， 以形成一个层次结构。</p>
<p>配置项（item）是最后一级目录了，它下面不可以再有目录：</p>
<img data-src="https://fanhua-picture.oss-cn-hangzhou.aliyuncs.com/01%E5%B5%8C%E5%85%A5%E5%BC%8F%E5%BC%80%E5%8F%91/02IMX6ULL%E5%B9%B3%E5%8F%B0/LV06-%E9%A9%B1%E5%8A%A8%E5%BC%80%E5%8F%91/LV06-12-ConfigFS-02-%E6%95%B0%E6%8D%AE%E7%BB%93%E6%9E%84%E4%B8%8E%E5%BA%94%E7%94%A8/img/image-20250316141505803.png" alt="image-20250316141505803" />

<p>我们可以在配置项组中创建目录，那么我们能否实现这样的结构：</p>
<figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">/sys/kernel/config/sconfigfs/sgroup/a_dir/item_name_dir</span><br></pre></td></tr></table></figure>

<p>下面就来了解一下多级目录的创建。其实吧，学到这里的时候我也不知道这里有什么用，后面用到了再补充吧。</p>
<h2 id="1-demo源码-3"><a href="#1-demo源码-3" class="headerlink" title="1. demo源码"></a><font size=3>1. demo源码</font></h2><p>源码可以看这里：<a target="_blank" rel="noopener" href="https://gitee.com/sumumm/imx6ull-driver-demo/tree/master/12_configfs_demo/06_multilevel_dir">12_configfs_demo&#x2F;06_multilevel_dir · 苏木&#x2F;imx6ull-driver-demo - 码云 - 开源中国</a></p>
<h2 id="2-开发板测试-3"><a href="#2-开发板测试-3" class="headerlink" title="2. 开发板测试"></a><font size=3>2. 开发板测试</font></h2><ul>
<li>（1）挂载configfs文件系统</li>
</ul>
<figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">mount -t configfs none /sys/kernel/config</span><br></pre></td></tr></table></figure>

<ul>
<li>（2）加载驱动</li>
</ul>
<figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">insmod sdriver_demo.ko</span><br></pre></td></tr></table></figure>

<ul>
<li>（3）创建目录</li>
</ul>
<figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br></pre></td><td class="code"><pre><span class="line">cd /sys/kernel/config/sconfigfs/sgroup/</span><br><span class="line">mkdir group_demo</span><br></pre></td></tr></table></figure>

<p>然后输入“mkdir group_demo” 命令创建 config_item ，创建成功之后 会打印这个项的名称：</p>
<img data-src="https://fanhua-picture.oss-cn-hangzhou.aliyuncs.com/01%E5%B5%8C%E5%85%A5%E5%BC%8F%E5%BC%80%E5%8F%91/02IMX6ULL%E5%B9%B3%E5%8F%B0/LV06-%E9%A9%B1%E5%8A%A8%E5%BC%80%E5%8F%91/LV06-12-ConfigFS-02-%E6%95%B0%E6%8D%AE%E7%BB%93%E6%9E%84%E4%B8%8E%E5%BA%94%E7%94%A8/img/image-20250313143111469.png" alt="image-20250313143111469"  />

<p>然后进入group_demo目录下， 此时可以在 test 目录下创建 item —— item_demo：</p>
<img data-src="https://fanhua-picture.oss-cn-hangzhou.aliyuncs.com/01%E5%B5%8C%E5%85%A5%E5%BC%8F%E5%BC%80%E5%8F%91/02IMX6ULL%E5%B9%B3%E5%8F%B0/LV06-%E9%A9%B1%E5%8A%A8%E5%BC%80%E5%8F%91/LV06-12-ConfigFS-02-%E6%95%B0%E6%8D%AE%E7%BB%93%E6%9E%84%E4%B8%8E%E5%BA%94%E7%94%A8/img/image-20250313143943356.png" alt="image-20250313143943356"  />

<p>但由于在驱动中我们并没有实现在 group 下创建 item 功能， 所以会提示创建 item_demo 没有权限。后面没有深入去搞了，这里就了解到这里吧。  </p>
<ul>
<li>（5）删除刚才的group_demo</li>
</ul>
<figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br></pre></td><td class="code"><pre><span class="line">cd /sys/kernel/config/sconfigfs/sgroup/</span><br><span class="line">rmdir group_demo</span><br><span class="line"><span class="meta prompt_"># </span><span class="language-bash">或者</span></span><br><span class="line">rm -rf group_demo</span><br></pre></td></tr></table></figure>

<img data-src="https://fanhua-picture.oss-cn-hangzhou.aliyuncs.com/01%E5%B5%8C%E5%85%A5%E5%BC%8F%E5%BC%80%E5%8F%91/02IMX6ULL%E5%B9%B3%E5%8F%B0/LV06-%E9%A9%B1%E5%8A%A8%E5%BC%80%E5%8F%91/LV06-12-ConfigFS-02-%E6%95%B0%E6%8D%AE%E7%BB%93%E6%9E%84%E4%B8%8E%E5%BA%94%E7%94%A8/img/image-20250313144138207.png" alt="image-20250313144138207"  />

<ul>
<li>（5）卸载驱动</li>
</ul>
<figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">rmmod sdriver_demo.ko</span><br></pre></td></tr></table></figure>

<blockquote>
<p>参考资料</p>
<p><a target="_blank" rel="noopener" href="https://www.cnblogs.com/sctb/p/13901054.html">configfs-用户空间控制的内核对象配置 - abin在路上 - 博客园</a></p>
<p><a target="_blank" rel="noopener" href="https://ldd.100ask.net/zh/12_USB/14_1.html">14_configfs的使用与内部机制 — Linux设备驱动开发教程中心</a></p>
<p><a target="_blank" rel="noopener" href="https://ldd.100ask.net/">Welcome to 100ask’s documentation — Linux设备驱动开发教程中心</a></p>
</blockquote>

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